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Biomedical subjects

J K Daniloff

Publications and source records attributed to J K Daniloff.

18 recordsLinked to original sources
PubMed1994

Labeled Schwann cell transplants versus sural nerve grafts in nerve repair.

This study evaluated the ability of Schwann cell transplants to enhance the recovery of function in injured nerves and compared the results to those produced by sural nerve grafts. Schwann cells were isolated from sciatic nerves, prelabeled with gold fluorescent dye admixed with collagen gel, and placed in resorbable collagen tubes. Twenty-four adult rats underwent severing of the bilateral sciatic nerves, with a 10-mm gap between the nerve stumps. The rats were then divided into two groups. A collagen tube with implanted Schwann cells was implanted in one leg of the Group I rats, and the contralateral leg served as a control and was repaired with a collagen tube filled with collagen gel only. The Group II animals received conduits packed with labeled Schwann cells in one leg to bridge the 10-mm gap; the contralateral leg was repaired with an autogenous sural nerve graft. Recovery of function was assessed physiologically and morphologically. Nerve conduction velocity and nerve action potential amplitude measurements showed that the Schwann cell implants induced return of function comparable to that of the sural nerve grafts. Morphological assessments of myelination suggested a tendency toward greater numbers of myelinated axons in Schwann cell implants than in sural nerve grafts. Anatomical analyses of gold fluorescent dye showed both high viability of prelabeled Schwann cells at 120 days after transplantation and migration as far as 30 mm away from the implant site.

Animals↗
PubMed1994

Activity of neural cell adhesion molecule (N-CAM) components: a review.

The neural cell adhesion molecule, N-CAM, is a well-characterized component of nervous system morphogenesis and histogenesis. It mediates aggregation of neurons by binding homophilically to N-CAM on apposing cells. Different forms are generated through alternative splicing of one gene and varied amounts of carbohydrate determine binding strength. This review summarizes results of contemporary studies which link N-CAM components with activity involving the maintenance and reorganization of the brain following injury. Current studies which suggest mechanisms of function are also included.

Alternative Splicing↗
PubMed1991

Comparison of nerve regeneration through different types of neural prostheses.

Rat sciatic nerve regeneration through three synthetic neural prostheses was compared with regeneration through nerve allografts. The synthetic prostheses were either nonpermeable nonabsorbable (Silastic), permeable absorbable (polyglactin mesh), or permeable nonabsorbable (polypropylene mesh). Animals were evaluated at 10, 24, and 90 days. Functional analysis of nerve regeneration was performed by noninvasive methods: electromyography and walking tracks. Nerve tissue was examined with routine histologic and immunofluorescent techniques. A compressive neuropathy developed with the use of the Silastic implant. A neutrophilic inflammatory infiltrate was consistently associated with implantation of the polyglactin mesh. A strong connective tissue response was noted around the polypropylene mesh. Early recovery of nerve function was seen with the Silastic implants, however, overall nerve function was best in the nerve allograft and polypropylene mesh groups. Polyglactin implantation increases the local inflammatory response and should not be used for nerve anastomoses. If Silastic entubulation is used, it should be removed between 24 and 90 days.

Animals↗
PubMed1991

A novel assay for the in vivo study of Schwann cells.

An in vivo assay was developed for long-term analyses of Schwann cells at the single cell level. Schwann cells were isolated from sciatic nerves and labeled with the fluorescent gold label Fluoro-Gold. Cells were then transplanted into severed sciatic nerves of young adult rats. Gold-labeled Schwann cells, identified by double-labeling with S100 antibodies, were observed up to 10 mm away from the transplant site and after 90 and 120 days of survival in vivo.

Animals↗
PubMed1990

Antibodies to the neural cell adhesion molecule disrupt functional recovery in injured nerves.

Tubes containing specific monoclonal antibodies to the neural cell adhesion molecule (N-CAM) were applied to transected sciatic nerves to attempt to perturb the recovery of muscle function. Physiological recordings were used to estimate the return of function. The decline of implanted antibody over 28 days was estimated and negatively correlated with the degree of functional recovery. No significant immune responses were detected in response to the implanted material. The data implicated N-CAM as a significant component of nerve regeneration.

Animals↗
PubMed1989

Expression of cytotactin in the normal and regenerating neuromuscular system.

Cytotactin is an extracellular glycoprotein found in a highly specialized distribution during embryonic development. In the brain, it is synthesized by glia, not neurons. It is involved in neuron-glia adhesion in vitro and affects neuronal migration in the developing cerebellum. In an attempt to extend these observations to the peripheral nervous system, we have examined the distribution and localization of cytotactin in different parts of the normal and regenerating neuromuscular system. In the normal neuromuscular system, cytotactin accumulated at critical sites of cell-cell interactions, specifically at the neuromuscular junction and the myotendinous junction, as well at the node of Ranvier (Rieger, F., J. K. Daniloff, M. Pinçon-Raymond, K. L. Crossin, M. Grumet, and G. M. Edelman. 1986. J. Cell Biol. 103:379-391). At the neuromuscular junction, cytotactin was located in terminal nonmyelinating Schwann cells. Cytotactin was also detected near the insertion points of the muscle fibers to tendinous structures in both the proximal and distal endomysial regions of the myotendinous junctions. This was in striking contrast to staining for the neural cell adhesion molecule, N-CAM, which was accumulated near the extreme ends of the muscle fiber. Peripheral nerve damage resulted in modulation of expression of cytotactin in both nerve and muscle, particularly among the interacting tissues during regeneration and reinnervation. In denervated muscle, cytotactin accumulated in interstitial spaces and near the previous synaptic sites. Cytotactin levels were elevated and remained high along the endoneurial tubes and in the perineurium as long as muscle remained denervated. Reinnervation led to a return to normal levels of cytotactin both in inner surfaces of the nerve fascicles and in the perineurium. In dorsal root ganglia, the processes surrounding ganglionic neurons became intensely stained by anticytotactin antibodies after the nerve was cut, and returned to normal by 30 d after injury. These data suggest that local signals between neurons, glia, and supporting cells may regulate cytotactin expression in the neuromuscular system in a fashion coordinate with other cell adhesion molecules. Moreover, innervation may regulate the relative amount and distribution of cytotactin both in muscle and in Schwann cells.

Animals↗
PubMed1986

Amer-Ind versus ASL: recognition and imitation in aphasic subjects.

The imitation and recognition ability of brain-damaged and normal subjects was tested for 30 pairs of semantically matched ASL signs and corresponding Amer-Ind gestures. Subjects were rated according to severity and site of lesion. They were 6 nonaphasic, right-hemisphere brain-damaged subjects, 12 aphasic subjects, and 12 non-brain-damaged geriatric subjects. Results indicated that the Amer-Ind gestures were significantly easier to imitate and to recognize than the matched ALS signs. The relationships between these gestural abilities and severity of aphasia, site of lesion, Amer-Ind transparency ratings, and subjects' performance on a standardized aphasia test are outlined. The theoretical implications that concern the neural systems which mediate spoken and limb gestures are discussed.

Aged↗
PubMed1986

Neuronal cell adhesion molecules and cytotactin are colocalized at the node of Ranvier.

Immunocytochemical methods were used to show that Ng-CAM (the neuron-glia cell adhesion molecule), N-CAM (the neural cell adhesion molecule), and the extracellular matrix protein cytotactin are highly concentrated at nodes of Ranvier of the adult chicken and mouse. In contrast, unmyelinated axonal fibers were uniformly stained by specific antibodies to both CAMs but not by antibodies to cytotactin. Ultrastructural immunogold techniques indicated that both N-CAM and Ng-CAM were enriched in the nodal axoplasm and axolemma of myelinated fibers as well as within the nodal regions of the myelinating Schwann cell. At embryonic day 14, before myelination had occurred, small-caliber fibers of chick embryos showed periodic coincident accumulations of the two CAMs but not of cytotactin, with faint labeling in the axonal regions between accumulations. Cytotactin was found on Schwann cells and in connective tissue. By embryonic day 18, nodal accumulations of CAMs were first observed in a few medium- and large-caliber fibers. Immunoblot analyses indicated that embryonic to adult conversion of N-CAM and a progressive decrease in the amount of Ng-CAM and N-CAM occurred while nodes were forming. Sciatic nerves of mouse mutants with defects in cell interactions showed abnormalities in the distribution patterns and amount of Ng-CAM, N-CAM, and cytotactin that were consistent with the known morphological nodal disorders. In trembler (+/Tr), intense staining for both CAMs appeared all along the fibers and the amounts of N-CAM in the sciatic nerve were found to be increased. In mice with motor endplate disease (med/med), Ng-CAM and N-CAM, but not cytotactin, were localized in the widened nodes. Both trembler and med/med Schwann cells stained intensely for cytotactin, in contrast to normal Schwann cells which stained only slightly. All of these findings are consistent with the hypothesis that surface modulation of neuronal CAMs mediated by signals shared between neurons and glia may be necessary for establishing and maintaining the nodes of Ranvier.

Animals↗
PubMed1986

Altered expression of neuronal cell adhesion molecules induced by nerve injury and repair.

Peripheral nerve injury results in short-term and long-term changes in both neurons and glia. In the present study, immunohistological and immunoblot analyses were used to examine the expression of the neural cell adhesion molecule (N-CAM) and the neuron-glia cell adhesion molecule (Ng-CAM) within different parts of a functionally linked neuromuscular system extending from skeletal muscle to the spinal cord after peripheral nerve injury. Histological samples were taken from 3 to 150 d after crushing or transecting the sciatic nerve in adult chickens and mice. In unperturbed tissues, both N-CAM and Ng-CAM were found on nonmyelinated axons, and to a lesser extent on Schwann cells and myelinated axons. Only N-CAM was found on muscles. After denervation, the following changes were observed: The amount of N-CAM in muscle fibers increased transiently on the surface and in the cytoplasm, and in interstitial spaces between fibers. Restoration of normal N-CAM levels in muscle was dependent on reinnervation; in a chronically denervated state, N-CAM levels remained high. After crushing or cutting the nerve, the amount of both CAMs increased in the area surrounding the lesion, and the predominant form of N-CAM changed from a discrete Mr 140,000 component to the polydisperse high molecular weight embryonic form. Anti-N-CAM antibodies stained neurites, Schwann cells, and the perineurium of the regenerating sciatic nerve. Anti-Ng-CAM antibodies labeled neurites, Schwann cells and the endoneurial tubes in the distal stump. Changes in CAM distribution were observed in dorsal root ganglia and in the spinal cord only after the nerve was cut. The fibers within affected dorsal root ganglia were more intensely labeled for both CAMs, and the motor neurons in the ventral horn of the spinal cord of the affected segments were stained more intensely in a ring pattern by anti-N-CAM and anti-Ng-CAM than their counterparts on the side contralateral to the lesion. Taken together with the previous studies (Rieger, F., M. Grumet, and G. M. Edelman, J. Cell Biol. 101:285-293), these data suggest that local signals between neurons and glia may regulate CAM expression in the spinal cord and nerve during regeneration, and that activity may regulate N-CAM expression in muscle. Correlations of the present observations are made here with established events of nerve degeneration and suggest a number of roles for the CAMs in regenerative events.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Differential distribution of cell adhesion molecules during histogenesis of the chick nervous system.

We have compared the expression of the neural cell adhesion molecule (N-CAM) and the neuron-glial cell adhesion molecule (Ng-CAM) during histogenesis of the chick nervous system. Data from immunohistochemistry and photometry were combined to construct maps of the overall distribution and dynamics of CAM appearance and disappearance. Each CAM appeared in a characteristic spatial and temporal pattern in various areas during cell movement, fiber outgrowth, tract formation, and myelination. N-CAM was more uniformly distributed than Ng-CAM and was present on all neural cell bodies and processes of the CNS and PNS. In the adult, the staining pattern of N-CAM remained similar to that in the embryo, although the staining intensity was diminished. During embryonic development, Ng-CAM was expressed on extending neurites and migrating neurons. The appearance Ng-CAM in the CNS was correlated particularly with times of cell migration in spinal cord and cerebellum, and in regions undergoing neurite extension, such as the developing white matter of the spinal cord, the optic nerve, and the medial longitudinal fasciculus. Cell bodies not undergoing migration were negative for Ng-CAM. In the adult CNS, Ng-CAM was markedly decreased in myelinated fiber tracts like the white matter of the spinal cord but persisted in unmyelinated regions such as the olfactory bulb. In contrast, in the PNS (for example, the dorsal root ganglion and sciatic nerve), Ng-CAM appeared early on both cell bodies and neurites, and it continued to be present on both in the adult, even in the presence of myelin. Maps comparing the relative distribution of Ng-CAM and N-CAM showed dynamic reversals as the nervous system developed and, as a result, the pattern of CAM expression was markedly different in embryos and adults. This difference appears to reflect changes in the roles of selective adhesion and of the two neuronal CAMs at different times of development.

Animals↗
PubMed1985

Cross-species embryonic septal transplants: restoration of conditioned learning behavior.

Embryonic septal and hippocampal tissue from mice was transplanted between species into the brains of adult rat hosts as cell suspensions. Deficits in the ability to learn a conditioned, hippocampally mediated, forced alternation behavior, which were caused by a bilateral transection of the fornix-fimbria pathway, were ameliorated in the septal transplant recipients. The successful performance of the task was correlated to the density index of acetylcholinesterase in the hippocampal section.

Acetylcholinesterase↗
PubMed1985

Cross-species neural transplants of embryonic septal nuclei to the hippocampal formation of adult rats.

In the absence of immunosuppressive treatment, suspensions of cells from the developing septal region of mouse embryos were transplanted successfully into the denervated hippocampal formations of adult rat hosts. The longitudinal recovery of acetylcholinesterase (AChE)-containing fibers in the host was the index of transplant success. In transplant recipients, the fornix-fimbrial interconnection between the septum and hippocampal formation was severed unilaterally, and two 5 microliter aliquots of cell suspension were injected into the hippocampal formations of host rats. Five sets of controls included one in which animals received no surgical intervention (Normal Controls), and another which was subjected to a sham operation (Sham Controls). The fornix-fimbria pathway was transected unilaterally in Lesion Control animals, while Hippocampal Controls received the same lesion plus two injections of non-cholinergic cells from the hippocampal formations of mouse embryos. Injection Controls were subjected to a fornix-fimbria transection and given two injections of debris and dead cells in saline. The cross-species transplants induced the return of a normal AChE laminar pattern in the recipient rats. The density of the laminar pattern, quantified with laser densitometry, was greatest in transplants that had survived for one week, but only in sections adjacent to the injection sites. Although the density decreased from the first through third weeks of survival, overall density of AChE staining stabilized from the fourth through 17th weeks of survival. Because the success rates of these cross-species transplants were similar to those reported for homogenic tissue, it was concluded that the rat brain is a suitable host for xenogenic transplants of septal neurons from embryonic mice.

Acetylcholinesterase↗
PubMed1984

Cross-species septal transplants: recovery of choline acetyltransferase activity.

Following interruption of the fornix-fimbria pathway, hippocampal choline acetyltransferase (ChAT) activity was restored gradually by cross-species cell suspension transplants of embryonic septum. The hippocampal segment closest to the implant reached 35% of normal 17 weeks after transplantation. The overall restoration of ChAT by xenogenic cell suspension had many similarities to that reported for homogenic solid and cell suspension septal grafts. The time course of the recovery of ChAT activity was different from the time course of the ingrowth of acetylcholinesterase stained fibers reported previously.

Animals↗
PubMed1984

Comparison between the motoric constraints for Amer-Ind and ASL sign formation.

Previous research has shown that Amer -Ind signals are more easily learned and remembered than their synonyms in American Sign Language. One possible reason is a difference in motoric complexity between the two systems. To test the hypothesis that such a difference exists, the positions and movements that constitute the 236 signals of Amer -Ind Code were compared with those of their synonyms in American Sign Language. It was found that the ASL signs were indeed more complex in terms of changes of hand orientation during production, the use of two hands rather than one, the number of different handshapes used, and the total amount of movement required. When the two systems were compared in terms of the normal development of finger, hand, and arm movements, it was found that more Amer -Ind signals than ASL signs are within the competence of infants at both the 6-month and 12-month levels. Relative to the motor coordination required to execute both systems, it was concluded that the Amer -Ind corpus is less complex than a matched group of ASL signs.

Deafness↗
PubMed1983

Amer-Ind transparency.

Objective and reliable transparency comprehension results have been obtained on the citation form of the 193 Amer-Ind signals as presented in the original Amerind Video Dictionary. Transparency ratings, as determined by three different scoring criteria, as well as the most common errors, are presented. While transparency (42-50%) was considerably less than what has been suggested in previous reports (80-88%) it was, nevertheless, well above what has been reported for signs from American Sign Language. Transparency of repetitive signals was significantly higher than that reported for kinetic and static signals. The implications for clinical practice are discussed.

Adult↗
PubMed1982

Gesture recognition in patients with aphasia.

This study focuses on the controversial issue of the integrity of gestural communication abilities in subjects with aphasia. To define the ability of subjects to interpret symbolic gestures, an Amer-Ind Recognition Test (ART) was developed which required no verbal response from the examiner or the subject. The relationships between impairment of Amer-Ind signal recognition and (a) severity of aphasia, (b) listening and talking abilities and (c) the type of response picture used were investigated. Whether subjects more often chose related foils than unrelated foils in a forced-choice format was also examined. Two training tests and the ART are described. Results from administration to 15 aphasic subjects indicated that: (a) all subjects performed equally well, regardless of their aphasia severity classification; (b) action picture recognition was related to listening ability; (c) action pictures were easier to identify than object pictures; and (d) on error responses, subjects overwhelmingly chose related over unrelated foils. The possibility that gestural abilities were relatively well preserved among the subjects tested, in the presence of a wide range of listening and talking deficits, is also discussed.

Adult↗